One of the latest missions from the ISS is kind of amazing. The High Definition Earth Viewing (HDEV) experiment consists of four cameras that have been attached outside of the ISS. Though temperature is controlled, the cameras are exposed to the radiation from the sun, which will allow astronauts to understand how radiation affects the instruments.

The experiment is being run in conjunction with High Schools United with NASA to Create Hardware (HUNCH) program that serves as outreach for students 9-12. Students participating in this program also helped design some aspects of the camera.

The cameras point down at Earth at all times, which makes for some breathtaking images. The feed will sometimes go down as the signal switches between the cameras, and it is hard to see when the ISS is on the dark side of the planet. If the cameras are down, the screen will be grey.

First the screen is just black, and you're wondering if it's working, then the two docked Soyuz light up, then the terminator creeps up slowly at the bottom of the screen before they switch to 'forward view'.